Automobile luggage rack

Abstract: A luggage rack (14) of the type suitable for installation on the roof (12) of an automotive vehicle (10) is improved through the addition of a mechanism for reducing the noise generated by wind passing over cross members (16,18) of the luggage rack (14). The mechanism is a strip (34) having irregular outer surfaces (40,42) secured to outer surfaces of at least one of the cross members (16,18). The irregular surfaces (40,42) operate to vary the cross section of the cross member (16,18) as it extends transversely of the vehicle (10), and the strip (34) may be formed as a tape having an adhesive layer (36) for securement to the luggage rack (14).

Description: The present invention relates generally to automobile luggage racks and more specifically to structure reducing wind noise propagated by movement of vehicles carrying such luggage racks. While the mounting of luggage racks on the roofs or deck lids of automotive vehicles has been found to be useful in expanding the load carrying capability of the vehicle, such devices particularly those mounted on roofs have the adverse effect of presenting a surface set off from the originally designed surface of the vehicle which is not consistent with the desired air dynamic approach of the vehicle design. The luggage racks generally include one or more transversely extending cross members which tend to disturb the flow of air over the roof of the vehicle and create perceptible noises within the vehicle, such as high pitch whistles or buzzes. This is particularly pronounced when the frequency of the wind load imposed on the cross member matches the natural frequency of the cross member. Responsive to this condition, automotive designers have attempted to modify the structure of the luggage racks by modifying the configuration of the cross member to reduce the noise effect. German Patent 2614365 discloses a design in which a mesh sleeve is put in surrounding relationship with respect to circular and rectangular cross section cross members. This approach has been found to not be aesthetically pleasing and requires a significant outlay in material and labour to fabricate and install the sleeve. Another approach taken to enhance noise reduction in roof mounted luggage racks is shown in U.S. Patent No. 4175682 to Bott. Bott teaches the use of an angularly adjustable tear drop cross section for the cross member to optimise the angle by which the cross member is presented to the air stream to minimise the noise effect. Disadvantageously this approach requires a significant complication in the design of the supports for the cross members and adds both direct assembly labour and developmental labour in performing and setting the desired adjustment. The Patent document DE-A-4 035 729 describes a roof mounted luggage rack having cross members supported on the roof by stanchions at each end of the crossmembers. The cross members are formed to incorporate a regular series of slots or apertures to control the flow of air past the cross members. The present invention provides a luggage rack with at least one transversely extending cross member that includes structure for defining the cross sectional shape of the cross member in a fashion that varies irregularly along the transverse extent of the cross member. Preferably the structure for defining the shape of the cross member is an irregularly shaped elongated strip secured to the cross member. It has been found that irregularly disturbing the flow of air over the cross member reduces wind noise by reducing the mutual amplification of laterally adjacent portions of the air flow. The present invention provides a luggage rack having means for reducing wind noise over its cross member that is simple to produce and assemble and which does not require significant development unique to a particular automobile. The invention will now be described further, by way of example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of the roof of the automobile on which is mounted a luggage rack according to the present invention; Figure 2 is a perspective view of the wind reducing strip according the present invention, Figure 3 is a cross sectional view taken along line 3-3 of Figure 1; and Figure 4 is a cross sectional view taken along line 4-4 of Figure 1. Turning now to the drawings in particular to Fig. 1 thereof, an automotive vehicle 10 is illustrated as including a roof 12 on which is installed a luggage rack indicated generally at 14. The luggage rack 14 is illustrated as comprising a pair of transversely extending cross members 16, 18, the cross member 16 being positioned near the front 20 of the vehicle 10, and the cross member 18 being positioned near the rear 22 of the vehicle 10. Each of cross members 16, 18 is simply supported by a pair of known stanchions 24, 26 in spaced relationship with respect to the roof 12. The precise configuration of stanchions 24, 26 is not important to the present invention, but in the preferred embodiments they are operative to support and maintain the cross members 16, 18 in vertically spaced relationship with respect to the roof 12 and to present the cross member in its generally tear drop shaped configuration as shown in Figs, 3 and 4 in facing relationship generally horizontally to the front of the vehicle 10. It is to be understood, however, that while the disclosed embodiment has a tear drop shaped cross sectional configuration that other shapes may be chosen within the teachings of the present invention. According to the preferred embodiment, the cross members 16, 18 include apertures 28 for receiving in snap-fit relationship a rub strip 30, preferably formed from an elastomer in order to present a non abrading surface 32 facing upwardly to support articles to be carried by the luggage rack 14. To reduce noise, induced by air flowing over the cross members 16, 18, there is provided a strip 34 which may be fabricated as a tape having an adhesive layer 36 secured to the underside 38 of at least the front cross member 16. The strip 34 is configured to present an irregularly shaped surface 40 to the air flowing underneath the cross member 16 and this irregular shape varies along the transverse axis of the cross member 16, as illustrated by the different surfaces 40, 42 shown in Figures 3 and 4. The degree of change that is necessary across the transverse extent of the cross member 16 may be established empirically when the natural frequency of the cross members 16, 18 are known. The strip 34 may be applied as by adhesively securing it to the surface 38 to ensure that the passage of air over the cross member 16, 18 does not excite that natural frequency. It is also possible to supplement or eliminate the noise reducing effect of the strip 34 by appropriately configuring the upper surface 32 of the rub strip 30 to modify the cyclical load input imposed by air flowing over the cross members 16, 18. While only certain embodiments of the luggage racks of the present invention are shown or suggested here, others may occur to those skilled in the automotive aerodynamic arts without departing from the scope of the following claims. In particular, other cross sectional shapes such as elliptical, square or rectangular may be chosen for the cross members (16,18).

Claims: A luggage rack for an automobile body comprising: at least one transversely extending cross member (16,18), and stanchion means (24,26) for supporting opposed ends of each cross member to position the cross member (16,18) in generally parallel, spaced relationship with respect to the automobile body, characterised in that means (34) are provided defining a cross-sectional shape of the cross member that varies irregularly along the transverse extent of the cross member. A luggage rack as claimed in claim 1, wherein the shape-defining means (34) is also operative to define an external surface (40,42) of the cross member (16,18) that is irregularly curved in the direction normal to the transverse extension of the cross member (16,18). A luggage rack as claimed in claim 1 or 2, wherein the shape-defining means (34) comprises an irregularly shaped elongated strip adhesively secured to the cross member (16,18). A luggage rack as claimed in claim 3, wherein the strip (34) is fabricated as a tape. A luggage rack as claimed in claim 3, wherein the cross-member (16,18) is generally tear drop shaped in cross section. A luggage rack as claimed in any one of the preceding claims, further comprising a second transversely extending cross member (16,18) longitudinally spaced from the at least one transversely extending cross member. A luggage rack as claimed in claim 6, wherein the tape (34) is applied to the surface of each of the cross members (16,18).

Inventors: OZOG ROBERT JOHN, OZOG, ROBERT JOHN
Applicants: FORD FRANCE, FORD MOTOR CO, FORD WERKE AG, FORD FRANCE S. A., FORD MOTOR COMPANY LIMITED, FORD-WERKE AKTIENGESELLSCHAFT
Application year: 1994
Main classification: B60R9
IPC codes: B60R9, B62D35